It is the aim of this proposal to obtain various Epstein-Barr virus (EBV)-determined antigens, especially the D (diffuse) and the R (restricted) components of the EBV-induced early antigen (EA) complex in sufficient quantity and purity to determine their nature and functions, to answer questions concerning the differential antibody responses to EA-D and EA-R observed in EBV-associated diseases which cannot be resolved by presently available immunofluorescence techniques, and to prepare monospecific antisera in animals for immune electron-microscopic study of the sites and temporal aspects of antigen synthesis in productively infected cells. These aims reduce development and use of serologic techniques suitable for detection of solubilized EBV-determined antigens such as immune-adherence hemagglutination and enzyme-linked immunosorbent assays which in turn might become more widely available than the complex immunofluorescence tests for the serodiagnosis of primary EBV infections as well as Burkitt's lymphoma and nasopharyngeal carcinoma and the monitoring of tumor patients following therapy. Attempts will be made also to find an explanation for the transient emergence of heterophile antibodies in infectious mononucleosis.